Foul

The foul rag that he used to clean the car only made it dirtier.

The photographer struggled to capture clear images in the foul lighting of the abandoned building.

The experiment went foul, resulting in inaccurate data.

The car's engine started running foul, causing it to sputter and stall.

The competitor accused his opponent of playing foul in the chess tournament.

The foul smoke from the burning forest obscured the sun and created a gloomy atmosphere.